Coloration of hot melt polymers

ABSTRACT

The invention concerns the coloration of hot melt polymers by direct injection of a dye into the polymer stream during polymerization, e.g., before feed to a spinning machine. A feed pump raises the dye pressure to approximate to that of the polymer at the injection point and a gear or turbine pump provides and controls continuous flow injection of the dye from the feed pump into the polymer stream. A three gear pump in a temperature-controlled zone is preferably used for dye injection and the polymer is bled upstream of the injection point for premixing with the dye in the three gear pump.

United States Patent [1 1 Hoyle et al.

[ COLORATION OF HOT MELT POLYMERS [75] inventors: John Hoyle; ThomasReuben Griffin,

both of Kegworth, near Derby,

[21] Appl. No.: 160,812

[52] US. Cl 259/4, 137/566, 137/567,

[451 Aug. 28, 1973 3,326,815 6/1967 Werner et a1 259/8 X PrimaryExaminer-William 1. Price Assistant Examiner-Phi1ip R. CoeAttorney-Young & Thompson [57] ABSTRACT The invention concerns thecoloration of hot melt polymers by direct injection of a dye into thepolymer stream during polymerization, e.g., before feed to a spinningmachine.

A feed pump raises the dye pressure to approximate to that of thepolymer at the injection point and a gear or turbine pump provides andcontrols continuous flow injection of the dye from the feed pump intothe polymer stream.

A three gear pump in a temperature-controlled zone is preferably usedfor dye injection and the polymer is bled upstream of the injectionpoint for premixing with the dye in the three gear pump.

2 Claims, 2 Drawing Figures 137/604, 259/6, 425/3822 [51] lnt.Cl. ..B01f5/14,B0lf 13/10 [58] Field of Search 137/566, 567, 604; 259/7, 8, 21,22, 23, 24, 18, 4, 60; 418/196; 425/382.2

[56] References Cited UNITED STATES PATENTS 3,023,764 3/1962 Dooley eta1. 137/566 X 3,272,141 9/1966 Curry et a] 418/196 X 2,915,299 12/1959Woebcke 259/8 Patented Aug. 28, 1973 3,154,134

COLORATION OF HOT MELT POLYMERS This invention relates to the colorationof hot melt polymers andhas for its object to provide improved apparatusfor the direct injection of a dye into a polymer stream duringpolymerization. It is of particular advantage in the coloration of hotmelt polymer immediately prior to the latter being fed to a spinningmachine.

According to the invention, apparatus for the coloration of a hot meltpolymer by direct injection of the dye, in solution or suspension, intoa continuous polymer stream temperature-controlled for progressivepolymerization, as in a continuous polymerization coil, comprises a feedpump for raising the dye pressure to approximate to that of the polymerat the injection point, and a gear or turbine pump for continuous-flowinjection of the dye from the feed pump into the polymer stream and formeasurement and control of the rate of injection.

The apparatus preferably includes a dye-mixing tank with continuouslyoperating agitating or stirring means therein and providing the input tothe feed pump. The dye pressure may then be-determined and controlled bymeans of a relief valve in a feed-back path from the output side of thefeed'pump.

In a preferred arrangement according to the invention, a three-gear pumpin a temperature-controlled zone is used for dye injection, and polymeris bled up stream of the injection point for preliminary mixing with thedye in the three-gear pump.

The invention provides for dye injection into a continuouspolymerization coil or the like in a continuous flow free of pulsationssuch as are-associated with piston or diaphragm pumps, and thereforemaking for uniform coloration. The gear-type pump providing thecontinuous-flow injection, being operated in a pressure-balancedcondition, also ensures accurate metering, making for good control ofcolor and of the facility of repeating a color.

Two forms of apparatus for the coloration of hot melt polymers,representing embodiments of the invention, will now be described by wayof example, and with reference to the .accompanying drawings, in which:

FIG. 1 illustrates the first of the forms of apparatus,

and a I v FIG. 2 illustratesthesecond formof apparatus.

In each case polymer salt flows through a continuous polymerization coil1 in a temperature-controlled zone and is delivered into a manifold 2supplying the individual metering pumps which feed the spinnerets ofaspinning machine. Colorization is achieved, with or without a measure ofpremixing, bydirect injection of a dye solution or suspension into thepolymer stream in the polymerization coil. Dispersement or finaldispersement of the dye in the polymer salt results from the violentboiling action of the salt in the coil.

In one embodiment the dye in a water orglycol solution or suspension isstored in a mixing tank 3 fitted with a rotary-paddle type agitator 4and with an outlet 5 connected to a feed and recirculating pump 6, theexcess pump capacity being recirculated back to the dye mixing tankthrough a line 7 and a relief valve 8 which controls the deliverypressure. This recirculation assists in agitation of the dye solution ordispersion. The dye passes from the feed-pump 6, at a pressuredetermined and controlled by the relief valve 8, to a two-gear injectionpump 9, the outlet 10 of which leads directly to a tapping point 11 inthe continuous polymerization coil 1 for dispersement of the dye asalready described.

In operation, the feed-pump pressure is adjusted to match the polymerpressure at the tapping point I] so that the two-gear injection pump 9operates in a pressure balanced condition. This ensures accuratemetering and permits effective control of the rate of injection.

In an alternative arrangement, a three-gear injection pump 12 in atemperature-controlled zone 13 is employed in place of the two-gear pump9 and partially polymerized salt from the continuous polymerization coil1 is bled from a point 14 upstream of the injection point 11 into thethree-gear pump 12 for pre-mixing. The pump 12 has a pair of inlet ports15 and 16 and a single outlet port. The three gears of the pump arearranged (as shown) for rotation about aligned parallel axes. Rotationof the gears effects mixing of the liquid flows entering through theinlet ports 15 and 16 and delivery thereof under pressure through theoutlet port.

In this arrangement, a dye feed-pump of controlled delivery pressure isemployed as before. It is coupled to one inlet port 15 of the three-gearinjection pump 12. The polymer salt bled from the coil 1 is fed to theother inlet port 16 so that a measure of premixing of the dye and thepolymer salt takes place in the three-gear pump 12, which is maintainedat a temperature above the melt temperature of the polymer being used.The threegear pump 12 injects the mixture into the continuouspolymerization coil 1 at injection point 11 so that final mixing isachieved by the boiling action within the coil.

In order to ensure accurate metering, the three-gear injection'pump 12is operated in a balanced pressure condition by adjusting the dye feedpressure to match the polymer pressure at the point of injection, andarranging the bleed tapping close to the injection point. (butsufficiently removed to minimize recirculation of the injected dye),sothat the pressure difference between the point of bleed and the pointof injection is small. 1

Premixing of the dye and polymer assists-in complete final dispersion ofthe dye. has a further advantage in that wear of the pump gearsisreduced when an abrasive dye additive is used as compared with handlingonly the dye in the injection pump.

. We claim:

1. Means for feeding colored hot melt polymer to the spinnerets of aspinning machine, said feeding means comprising a polymerization coilthrough which the hot melt polymer is delivered to the spinnerets, saidcoil having an injection 'point; a rotary pump; a line connecting therotary pump to the injection point; a dye mixing tank; and a feed pumpfor delivering concentrated dye under a predetermined controllablepressure directly from the tank to the rotary pump for continuous flowinjection of the concentrated dye into the hot melt polymer passingthrough the coil.

2. Means for feeding colored hot melt polymer to the spinnerets of aspinning machine, said feeding means comprising a polymerization coilthrough which the hot melt polymer is delivered to the spinnerets, saidcoil having an injection point and a bleed point disposed upstream ofthe injection point; a rotary pump having amixing facility, said rotarypump having a pair of inlets and an outlet; a supply line connecting thebleed point and one of the inlets of the rotary pump; a'delivery lineconnecting the outlet of the rotary pump and 3 4 the injection point; adye-mixing tank;and a feed pump fed to the rotary pump along the supplyline to obtain for delivering concentrated dye under a predeterminedcontinuous flow injection of colored polymer along the controllablepressure from the tank to the other inlet of delivery line into thepolymerization coil. the rotary pump for admixture with hot melt polymer

1. Means for feeding colored hot melt polymer to the spinnerets of aspinning machine, said feeding means comprising a polymerization coilthrough which the hot melt polymer is delivered to the spinnerets, saidcoil having an injection point; a rotary pump; a line connecting therotary pump to the injection point; a dye mixing tank; and a feed pumpfor delivering concentrated dye under a predetermined controllablepressure directly from the tank to the rotary pump for continuous flowinjection of the concentrated dye into the hot melt polymer passingthrough the coil.
 2. Means for feeding colored hot melt polymer to thespinnerets of a spinning machine, said feeding means comprising apolymerization coil through which the hot melt polymer is delivered tothe spinnerets, said coil having an injection point and a bleed pointdisposed upstream of the injection point; a rotary pump having a mixingfacility, said rotary pump having a pair of inlets and an outlet; asupply line connecting the bleed point and oNe of the inlets of therotary pump; a delivery line connecting the outlet of the rotary pumpand the injection point; a dye-mixing tank; and a feed pump fordelivering concentrated dye under a predetermined controllable pressurefrom the tank to the other inlet of the rotary pump for admixture withhot melt polymer fed to the rotary pump along the supply line to obtaincontinuous flow injection of colored polymer along the delivery lineinto the polymerization coil.